RADICAL CHAIN COPOLYMERIZATION OF METHYL METHACRYLATE AND OF STYRENE WITH C_(60) FORMS BRANCHED STRUCTURES

摘要

Soluble polystyrene and poly(methyl methacrylate) (PMMA) containing Ceo have been prepared by radical chain reactions in bulk and in solution. 1"7 As much as 50 weight percent of C60 has been incorporated into polystyrene, and weight average molecular weights as high as 20,000 have been found for polystyrene containing 30 weight percent Cgo-6 It is surprising that polymers are even produced, because benzyl, methyl, and tert-butyl radicals add to Ceo at rate constants of iO8-109 M1 s1, 811CP times greater than the rate constants for propagation of polystyryl and PMMA radicals,10 and greater than the rate constants of biraolecular termination of polymerization of styrene and MMA.10 Here we report analyses of the compositions and molecular weight distributions of polystyrene and PMMA containing C60 by multi-detector size exclusion chromatography (SEC) that prove branched structures, and suggest possible mechanisms for their formation.